Treatment of artificial materials



UAHON OF TtXTlLtS 6: NEWS,

Patented May 12, 1942 TREATMENT OF ARTIFICIAL MATERIALS No Drawing. Original application May 8, 1940,

Serial No. 333,936. Divided and this applica- UNITED STATES PATENT OFFICE tion December 27, 1940, Serial No. 372,004. In Great Britain May 23, 1939 2 Claims.

This invention relates to the treatment of artificial materials, and more particularly to proc esses for improving the properties, especially the extensibility, of artificial filaments, threads, yarns, fabrics, ribbons and the like made of or containing an organic derivative of cellulose. This application is a division of our application S. No. 333,936, filed May 8, 1940.

It is known that it is a matter of considerable importance to weaving, knitting, twisting and other textile operations that filaments, threads, yarns, and like materials should have a substantial extensibility, preferably an extensibility of 10 to 12 or 15% or more. It has been disclosed in U. S. Patent No. 2,058,422 that the treatment of artificial materials having a basis of an organic derivative of cellulose with organic solvents, swelling agents or latent solvents, in the absence of tension sufficient to stretch the materials, serves to increase their extensibility. The selection of the agents to be employed in this process is a matter of great importance and is determined by a number of factors involving elaborate research. The most important consideration, which weighs very heavily with the manufacturer, is that of reproducibility or control of results, and this is a particularly important matter when dealing with textile fabrics and like materials, since quite small variations in physical characteristics, especially extensibility, occurring over the length of such materials are shown up very clearly in fabrics formed therefrom, e. g. by the faults which arise from uneven tension during the fabric-forming operation. The over-all efficiency of the agents, their toxicity, and economic factors generally also come into consideration.

We have now found that methyl propionate is a highly satisfactory agent to employ for the purpose of increasing the extensibility of textile materials and the like having a basis of an.organic derivative of cellulose. It is found that methyl propionate gives advantageous results in the absence of any diluent. In other words, this agent can be employed with effective control of the process with any particular materials, provided, of course, that the temperature of treatment is maintained constant.

According to the invention, therefore, artificial filaments, threads, yarns, fabrics, ribbons and the like made of or containing an organic derivative of cellulose are subjected, in the absence of tension suflicient to stretch them, to the action of methyl propionate.

Preferably, the treatment is carried out while the filaments or other materials are under no tension or under only a slight tension so that they are substantially free to shrink under the influence of the treatment agent. If the agents are applied while the materials are under relatively high tension, the tension should subsequently be reduced or removed so that the materials are allowed to shrink while still under the influence of the agents.

The treatment agent may be employed alone or in admixture with other suitable agents, e. g. the lower alkyl formates or propylene chloride. Suitable diluents are, for example, glycol, glycerol and other hydroxy compounds which are substantially without action on the materials. Preferably, however, water-immiscible liquids are used as diluents, examples of which are benzene, toluene, xylene and other cyclic hydrocarbons, benzine, petroleum ether, kerosene and other allphatic hydrocarbons, carbon tetrachloride, perchlorethylene and other chlorinated or halogenated compounds which are inert or substantially inert towards the cellulose derivatives. Again, relatively high boiling diluents, e. g. tetrahydronaphthalene and decahydro naphthalene, may be employed. It will be understood, however, that, in general, diluents are not employed with the methyl propionate.

The concentration in which the treatment agent is employed and the temperature of working will depend upon the particular cellulose derivative which is present in the filaments or other materials to be treated, upon the physical characteristics of those materials and upon the degree of modification of the physical characteristics which is desired. Preferably, the shrinkage effected does not exceed about 20 or 25% and it is generally most advantageous to effect a shrinkage of 10 to 15%. Shrinkage may be restricted by suitable modifying the treatment medium, as regards composition, concentration and/or temperature, and/or by treating the materials while they are under sufhcient tension to prevent more than the desired shrinkage, the tension being maintained so long as the materials remain under the influence of the treatment agent.

When treating materials having a basis of acetone-soluble cellulose acetate, it is found that a satisfactory increase in extensibility can be secured by treating them in the absence of tension with a medium consisting of pure methyl propionate at ordinary temperatures, i. e. about 10-25 or 30 C.

The treatment agent according to the invention may be employed in any of the methods described, for example, in U. S. Patents Nos. 2,070,-

583 and 2,058,422. The invention is of the greatest importance when applied to filaments, threads, yarns, fabrics, ribbons and the like containing or derived from high tenacity wet-spun materials or materials which have been stretched to 200% or more of their original length in hot water or wet steam or in a medium containing an organic solvent or swelling agent. It will be understood, however, that the invention is not limited to the treatment of these materials, but is applicable generally to organic derivative of cellulose materials the extensibility of which it is desired to increase. It has further been found that the treatment agent according to the present invention imparts to staple fibres, particularly such as have been formed by cutting operations, a crinkled or crimped effect, which greatly enhances their spinning qualities.

Reference has been made above to materials having a basis of acetone-soluble cellulose acetate and the invention is of the greatest importance in connection with the treatment of such materials. However, materials made from other cellulose acetates or other esters of cellulose such as, for example, cellulose formate, propionate and butyrate, and mixed esters, e. g. cellulose acetopropionate and acetobutyrate, and also from cellulose ethers, e. g. methyl, ethyl and benzyl cellulose, or from cellulose ether-esters, may be treated.

The following example illustrates the invention:

Example Dry-spun cellulose acetate yarn, which has been stretched in wet steam to 1000% of its original length, is immersed for ten minutes at 20 C. in hank form in a bath of methyl propionate and is allowed to shrink freely. The yarn is then washed with a low-boiling petroleum ether and dried in a current of warm air. The product is found to be uniformly shrunk and to have an improved extensibility.

Having described our invention, what we desire to secure by Letters Patent is:

1. Process for increasing the extensibility of artificial filamentary materials made of or containing an organic derivative of cellulose, which comprises subjecting such filamentary materials which have been stretched in the presence of wet steam to'1000% of their original length to increase their tenacity, to immersion for ten minutes at 20 C. in a bath of methyl propionate, in the absence consisting solely of tension suflicient to stretch said filamentary materials, whereby said filamentary materials are shrunk by 10 to 15% of their length and their extensibility is increased.

2. Process for increasing the extensibility of artificial filamentary materials made of or containing cellulose acetate, which comprises subjecting such filamentary materials which have been stretched in the presence of wet steam to 1000% of their original length to increase their tenacity, to immersion for ten minutes at 20 C. in a bath of methyl propionate, in the absence consisting solely of tension sufiicient to stretch said filamentary materials, whereby said filamentary materials are shrunk by 10 to 15% of their length and their extensibility is increased.

DAVID JAMES HADLEY. THOMAS JACKSON. 

